Analysis of operation conditions for a pilot-scale supercritical CO ₂ extraction of diterpenoid from Pteris semipinnata L.

A pilot-scale supercritical CO ₂ extraction process with extraction volume of 20 L was established with which the antitumor diterpenoid, ent-11α-hydroxy-15-oxo-kaur-16-en-19-oic-acid, was extracted from the medicinal herb Pteris semipinnata L. The experiments showed that many factors had great impacts on yields of the diterpenoid, such as extraction temperature, pressure, fluid flow rate, extraction time and modifier. For the extraction process of the diterpenoid from Pteris semipinnata L, the optimum operation conditions were as follows: extraction temperature of 55°C, extraction pressure of 30 MPa, supercritical CO ₂ flow rate of 160 kg/h, extraction time of 4 h, and 10% ethanol as the modifier. Under such a condition, the diterpenoid was almost completely extracted from the material, and the yield was approximately 0.504 g/kg dry herb by high-performance liquid chromatography analysis. The yield was approximately 2.8-fold more than that of the normal solvent extraction. The experimental results demonstrate that the supercritical CO ₂ extraction process is rapid, highly efficient and with less consumption of organic solvents.